A Bold Plan to Reshape the Central Valley Flood Plain

Jacob Katz, a Ph.D candidate at the University of California, Davis, at an experimental flood plain.Credit
Noah Berger for The Bay Citizen

Jacob Katz stood shin-deep in a flooded rice paddy that is often dried out at this time of year. He thrust his hand into a writhing mass of baby salmon in his net and plucked three of the silver fry from the wind-whipped water’s surface.

In late January, five acres of this farmland in Yolo County was flooded and stocked with thousands of weeks-old Chinook salmon. It was the beginning of a three-year experiment that conservationists and government officials hope will provide scientific data to help guide a sweeping transformation of riverfront lands throughout the Central Valley, California’s prolific farming region.

“They were about two-thirds this size when we put them in,” said Mr. Katz, a doctoral candidate at the University of California, Davis, as the plump fry flapped off his palm and into the water. “They’re growing very, very rapidly. They’re looking great. It’s exactly what we want to see.”

An ambitious draft flood-prevention plan, published in December by the California Department of Water Resources, would re-engineer the valley’s network of rivers, canals and levees in an effort to prevent floods, restore wildlife habitat and protect water supplies for millions of people in the Bay Area and other parts of California. The plan, which calls for reversing the effects of 160 years of ad hoc levee building in the Central Valley, is a response to the deadly 2005 floods in New Orleans that followed Hurricane Katrina. Experts say a collapse of the Central Valley levees could cause similar devastation in California.

Yet the plan would take decades and cost tens of billions of dollars in local, state and federal money. It could also sink tens of thousands of acres of agricultural land under water, including parts of the Knaggs Ranch rice farm, where the baby salmon are growing along the Sacramento River.

Some farmers are angry because the plan, they said, enhances the environment and protects urban dwellers from floods at the expense of agricultural jobs and the rural economy. They also criticized state planners for failing to identify which parcels of land would be affected.

Jay Punia, executive officer of the Central Valley Flood Protection Board, which is charged with reviewing and approving the plan by July 1, said information about affected lands and other details about habitat restoration strategies sought by environmentalists would come after the draft is approved.

The baby fish in Mr. Katz’s net had spent three weeks in the experimental flood plain feasting on plankton and insects that young salmon historically relied upon to build their strength before venturing down rivers, through San Francisco Bay and into the Pacific Ocean.

Such nursery-style flood-plain habitats have nearly disappeared from the Central Valley. The creeks and rivers that carry rainwater and snowmelt from the Sierra Nevada and into the West Coast’s largest estuary were tamed long ago, lined with earthen levees that protect farms and a growing number of neighborhoods from the widespread flooding that defined the region until the middle of the 19th century.

Salmon, steelhead trout, Sacramento splittail and other native fish are not the only wildlife that flourish in the few remaining Central Valley flood plains. The habitats provide breeding, resting and feeding places for birds, including those that migrate along the heavily traveled avian highway between Mexico and Alaska, colloquially dubbed the Pacific Flyway.

Most of the levees, built as mounds of silt, sand and other materials found close to the riverbank, are in danger of collapsing. The Central Valley’s flood risks are considered among the most acute in the nation.

Photo

The flood plain was stocked with baby Chinook salmon.Credit
Noah Berger for The Bay Citizen

Such disasters could jeopardize $70 billion worth of property and infrastructure, put one million people at risk and contaminate or sever much of the state’s water supply, the Department of Water Resources estimates. Floods in 1983, 1986, 1995 and 1997 caused hundreds of thousands of people to be evacuated from their homes and resulted in more than $3 billion damage.

Until levee construction began in 1850, winter rains and melting snow would frequently cause rivers in the Central Valley to overflow. Shallow floodwaters teeming with wildlife would engulf the valley, flushing south and west until converging at the delta of the Sacramento and San Joaquin Rivers near Antioch, before gushing down into Suisun, San Pablo and San Francisco Bays.

Now, the more than 1,500 miles of levees confine most young salmon to river channels, where they are preyed upon as they grow by larger fish, including invasive striped bass, and are forced to battle currents as they hunt for midges, zooplankton and other food that was easier to find in the long-lost flood plains.

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“There’s more to eat on a flood plain than there is in a river,” Mr. Katz said. “It’s warmer, and that’s better for the metabolism of salmon.”

The loss of spawning and flood-plain habitats has contributed to a near-collapse of salmon in the region. Hatchery-raised fish now dominate and sustain many of the salmon populations, but those fish have been found to have genetic weaknesses and other ailments that can exacerbate the species’ woes.

The experimental site is part of the Yolo Bypass, a managed plain that floods after winter storms douse the northern part of the state on an average of 6 years out of every 10. Researchers plan to spend three winters measuring how different approaches to managing the creek-front lands affect salmon growth rates.

The Yolo Bypass flood plain overlaps private and public land, including rice fields, duck hunting clubs and protected habitat. It works as a relief valve, absorbing water in wet years, preventing that water from knocking down or cascading over levees and rushing into populated areas.

Under the draft Central Valley Flood Protection Plan, and also under the department’s draft Bay Delta Conservation Plan, which seeks to balance economic and environmental uses of water, the flood plain would be expanded and could flood every year. Other flood plains would be created or expanded throughout the region to help restore riverside habitats and reduce flood risks. In some cases, levees would be set back farther from rivers, creating flood buffers and shallow flood-plain-style habitat.

The proposed overhaul would cause the loss of 10,000 acres of farmland, according to preliminary estimates. An additional 30,000 acres would be frequently inundated.

If they expand the Yolo Bypass, “it’s going to bring all my ground inside the bypass,” said Tim Miramontes, a farmer who grows rice and other crops on 1,500 acres of land that he leases near Knaggs Ranch. “Potentially, I could lose all of it.”

Senator Lois Wolk, Democrat of Davis, one of the authors of the 2007 legislation that led to the flood planning process, acknowledged that the plan would be expensive and painful to put into action. But she said the risks of doing nothing could be far worse.

“It is a dramatic plan,” Ms. Wolk said. “The state taxpayer is liable for any damage that occurs if we haven’t fixed the levees. Not only is the taxpayer’s pocketbook at risk, but the cost in lives and disruption would be dramatic — worse, much worse, than Katrina.”

jupton@baycitizen.org

A version of this article appears in print on March 2, 2012, on Page A21A of the National edition with the headline: A Bold Plan to Reshape the Central Valley Flood Plain. Order Reprints|Today's Paper|Subscribe